Glasses for lithography and lithography for glasses Miroslav VLCEK

Department of General and Inorganic Chemistry Faculty of Chemical Technology University of Pardubice, 532 10 Pardubice Czech Republic 1

Goals of IMI-NFG: •International Colaboration with Research Trust on 6 new Functionalities •Multimedia Glass Education delivered across the boundaries •Outreach/Networking Glass Lecture Series: prepared for and produced by the International Material Institute for New Functionality in Glass An NSF sponsored program – material herein not for sale Available at www.lehigh.edu/imi

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Questions • What is lithography? What is glass? • Can glass be photosensitive? • Can glass be selectively etched/featured? If yes, how and what is the resolution limit? • Can a glass be applied in lithographic process and vice versa can lithography be applied to structure glasses?

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Lithography – what does it mean? in ancient Greek:

lithos = stones

graphia = to write

discovered by Alois Senefelder (Prague, Bohemia currently Czech Republic) in 1796 • oil-based image painted on the smooth surface of limestone • nitric acid (HNO3) emulsified with gum arabic burns the image only where surface unpainted and gum arabic sticks to the resulting etched area. • printing – water adheres to the gum arabic surface and avoids the oily parts, oily ink used for printing is doing exactly opposite, positive image is transferred on paper

http://sweb.cz/galerie.litografie/

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„Technical“ understanding of term lithography these days: formation of 3-D relief images in a film on the substrate with the aim of transferring them subsequently to the substrate Microlithography – pattering method which allows features smaller than 10 μm to be fabricated Nanolithography – pattering on a scale smaller than 100 nm Contact and/or proximity lithography – photomask in direct contact with structurised resist-coated substrate and/or small gap between them Maskless lithography - no mask is required to generate the final pattern – examples: electron beam lithography – final patterns are created from digital representation, computer controls scan of an electron beam across a resist-coated substrate interference lithography 5

What lithography involves? - an exposure (irradiation) source - a mask and/or computer controled scan of suitable beam across resist-coated substrate - a resist itself - know how of a series of fabrication steps that would accomplish pattern transfer from the mask to resist and subsequently to substrate on which device is fabricated

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How resists work? resist – radiation sensitive material, where chemical reactivity of exposed parts is modified relative to unexposed parts Etchant – agent (solvent, gas) which preferentially etches the exposed parts

the unexposed parts

positive etching

negative etching

original patterns are thus transferred into the resist after that substrate is patterned in resist-notcovered regions only all resist removed from corrugated substrate

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positive etching

negative etching resist SiO2 Si mask

exposure

etching of resist

etching of SiO2

resist removal 8

Most important parameters of any resist Sufficient sensitivity to some radiation and proper technology of selective etching (simpler is better) Resistent to agents applied for substrate etching High resolution – nano better Easy to be deposited – homogenous in properties and thickness

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What is glass? Glass – solid matter which is produced when the viscous molten material cools very rapidly to bellow its glass transition temperature and there is not sufficient time for atoms to form regular crystal lattice Silica based glasses – most common type of glasses about 70 % by weight of SiO2 soda-lime glass (≈ 30 % Na2O + CaO) borosilicate glass (≈ 10 % B203) lead crystal (at least 24 % of PbO) brittle, under compression can withstand a great force, chemically quit resistant, stable 3D compact structure, strong Si-O bonds obsidian – natural glass

10 http://www.galleries.com/minerals/mineralo/obsidian/obsidian.htm

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chandelier in Capital, Washington

New York – Trump Tower and Times Square

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But go back a little bit to science

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Chalcogenide glasses - nonoxide glasses O replaced by S, Se or Te - significantly lower Tg than oxide glasses - transmission in IR - high refractive index (≈ 1,8 – 3,2) - !!! sensitive to different radiation!!!

Ge40 S60

As10Ge30S60

IRel

As20Ge20S60

As30Ge10S 60

As40S 60

5 I. D. Aggarwal, J. S. Sanghera Journal of Optolectronics and Advanced Materials Vol. 4, No. 3, September 2002, p. 665 - 678

10 λ (μm)

15

20

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R. Ston, M. Vlček, H. Jain: J. of Non-Cryst. Solids 326&327 (2003) 220 – 225

Tailoring the properties

M. Vlcek, A.V. Stronski, A. Sklenar, T. Wagner, S.O. Kasap Journal of Non-Crystalline Solids 266-269 (2000) 964-968

Adopted from A. Feltz:Amorphous Inorganic Materials and Glasses, VCH, 1993, Berlin, Germany

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M.Vlček, A.V. Stronski, A. Sklenář, T. Wagner, S.O. Kasap: Journal Non-Cryst. Solids 266-269 (2000) 964-968

Tailoring the properties

Fig. 5. a Absorption coefficient as a function of the photon energy for the three chalcogenide glassy compositions, As40S40Se20 (this work), As40S60 and As40Se60. b Determination of the optical gap, Egopt , in terms of the Tauc law E. Marquez, J.M. Gonzales-Leal, R. Prieto-Aleon, M. Vlcek, A. Stronski, T. Wagner, D. Minkov Appl. Phys A 67 (1998) 371

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!!! CHG sensitive to different radiation!!! What is the reason of sensitivity of CHG? generally – all amorphous materials thermodynamically metastable exposure to suitable radiation can cause transformation in their structure or reaction with the environment (O2, metal, ....) → optical and physico-chemical properties including chemical resistance are influenced 17

Classification of radiation induced processes in amorphous chalcogenides Structural changes: - changes of local atomic configuration - polymerization – creating new bonds - phase changes, including crystallization Physico-chemical changes: - decomposition - photo-vaporization - photo-dissolution of certain metals - thermoplastic changes All these processes can result in changes of optical and physico-chemical properties 18

exposure with suitable radiation can change optical properties (T, R, n, α ...)

M. Vlček, C. Raptis, T. Wagner, A. Vidourek, M. Frumar, I.P. Kotsalas, D. Papadimitriou: Journal NonCryst Solids192-193 (1995) 669-673

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Exposure with suitable radiation can change chemical resistance What does it mean „suitable radiation“? band gap light (≈ 1 – 2.3 eV) UV or even visible light e - beam flux of ions X –ray.... both dry and wet etching can be applied Wet etching – all photoinduced processes can be applied Dry etching – usually photo-dissolution of certain metals is applied 20

DRY ETCHING

Plasma of ionized gases used to blast away atoms from the surface of the sample. (Also known as plasma etching) harsh conditions in plasma requires hard photoresist ! including: • high contrast of pattering • resistance to aggressive, ionied gases www2.ece.jhu.edu/faculty/andreou/495/2003/LectureNotes/DryEtching.pdf

Certain metals usually added to CHG photoresist – Why? combine photostructural and compositional changes from photodiffusion of metal (mainly Ag) in ChG is the solution !!!21

• High contrast of resist pattering wanted Ag diffuses transversally only, no lateral diffusion • resistent to plasma etching gas • resistance increases due to formation ternary Ag-As-S glass but in exposed parts only

As35S65

Ag diffuses into As-S step like - depth of diffusion - function of exposure dose Drawbacks – two more steps: • deposition of Ag • removal of excess Ag from unexposed

2 glass forming regions

Ag

As-S

As-S

≈AgAsS2 22

All Dry Process or combined process CHG Ag mask

Ag-As-S

¾deposition of As-S ¾deposition of Ag ¾exposure (vertical transfer of Ag into As-S) ¾removal of excess Ag from unexposed parts by dry/wet

Ag-As-S Ag-As-S

etching

¾dry/wet etching of As-S ¾dry/wet etching of substrate ¾dry/wet removal of Ag-As-S layer from exposed

parts 23

bilayer photoresist Ag + As (and/or Ge) based chalcogenide glass exhibit excellent resolution, high contrast and good resistance to dry etching by CF4 (+ O2)

www2.ece.jhu.edu/faculty/andreou/495/2003/LectureNotes/DryE tching.pdf

Sensitization - evaporation of Ag 200 W Hg lamp, 60 mW/cm2 excess Ag removed in HNO3-HCl-H2O 0.5 Torr CF4 gas, 100 W rf power etching rates: undoped 55 nm/sec Ag photodoped 0.15 nm/sec A. Yoshikawa Appl.Phys.Lett. 36(1) 107

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Patterning Options for dry etching Different sources !!! UV or visible light e - beam

X – ray beam

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Dry etching Negative dry etching of Ag-As2S3 bilayer resist by CF4/O2

A. Kovalskiy, M. Vlcek, H. Jain, A. Fiserova, C.M. Waits, M. Dubey Development of chalcogenide glass photoresists for gray scale lithography Journal of Non-Crystalline Solids 352 (2006) 589–594

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Dry etching of shaped structures - Ag diffuses into As-S glass in step like fashion - depth of diffusion - function of exposure dose

Profilogram demonstrating the change of etching depth with gradual variation of transparency of mask fragments.

Optical Profiler image demonstrating the possibility of smooth shaping with lens-like mask by photoinduced Ag diffusion into As2S3 film with following dry etching (reverse image, depth of etching 200 nm). CF4 as the etchant gas, with pressure of 100 mTorr, an electrode power of 110 W, CF4 flow rate of 100 sccm and an etching time of 2 min

27 A. Kovalskiy, H. Jain, J. Neilson, M. Vlcek, C.M. Waits, W. Churaman, M. Dubey On the mechanism of gray scale patterning of Ag-containing As2S3 thin films Journal of Physics and Chemistry of Solids 68 (2007) 920-925

Photodoping Phenomenon for Enhanced Selectivity Chalcogenide Layer Silver Layer Silver - Chalcogenide Layer

substrate

substrate

substrate

substrate

(b)

(c)

substrate

(a)

substrate

substrate

substrate (d)

(a) (b) (c) (d) (e) (f)

substrate

substrate (e)

substrate

substrate (f)

Deposition of chalcogenide layer Deposition of silver layer Exposure through mask Silver diffusion Removal of remaining silver Removal of chalcogenide regions to create photoresist 28

a

b

d

e

f

Photodiffusion enhanced lithography – when to use it??? hard resists applications Bilayer photoresist ⇒ more complicated technology BUT higher sensitivity and selectivity for both, wet and dry etching combine photostructural and compositional changes from photodiffusion of metal (mainly Ag) in ChG

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Dry etching of pure CHG possible too

diluted CF4 must be applied W. Li at al. J. Vac. Sci. Technol. A 23 (6) (2005) 1626 - 1632

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WET ETCHING

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amorphous chalcogenides

insoluble in acid solutions

relatively well soluble in alkaline solvents

dissolution rate in alkaline solvents can be influenced by exposure both, positive and negative etching can be achieved (even without Ag diffusion) 32

Parameters influencing selectivity of wet etching Sample composition, method and conditions of thin films preparation Prehistory of sample – virgin vs annealed Exposure conditions (I, λ, T, τ, environment...) Etching conditions (composition of etching bath, pH, temperature..)

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Method and conditions of thin films preparation all amorphous materials - thermodynamically metastable

thin layers farther from the equilibrium than bulk • vacuum evaporation fast condensation of fragments that exist only in vapour state – final structure influnced by vdep, p, substrate temperature, rotation of substrate.. • PE - CVD deposited at low temperature, H2 is incorporated in samples prepared by PE – CVD • spin coating deposited at low temperature, residual amount of the dissolver is „captured“ in the structure

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Prehistory of the sample virgin vs annealed

M. Vlcek Ph.D. Thesis

Ge30S60In10, 1,2 – non-irradiated, 1´,2´- irradiated, 2,2´previously annealed at 430 K Z.G. Ivanova: Proc. of Int. Conf. Amorphous Semiconductors, Gabrovo, 1984, Vol. 2, p. 268 35

Etching bath

Aqueous base Positive etching

Organic amine base Negative etching 36

What is the fundamental cause of sensitivity and changes in chemical resistance? Different CHG composition and different sources of radiation - different reason, let us discuss only most common case – band gap exposure photosensitivity of as-evaporated As-S thin films vacuum evaporation -fast condensation of fragments that exist only in vapour state

As2 S3

0,24 0,22

AsS3

0,20

I (arb. un.)

0,18 0,16 0,14

AsS3

As40S60

pyramids

As-As

↔ As-As

crystal

Bulk

0,12

amorphous

Annealed

0,10 0,08

Felc A : Amorfnye i stekloobraznye tvjordye neorganičeskie tela "MIR" Moskva (1986) 283

Exposed

0,06 0,04

Virgin

0,02 0,00 100

200

300

400

500

S-S 600

-1

ν (cm )

As2S3 orpiment

As4S4 realgar

cages

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Sn chains

What is the fundamental cause of sensitivity and changes in chemical resistance? vacuum evaporation - fast condensation of fragments that exist only in vapour state As42 S58 AsS3 As-As

↔ As-As

photoinduced changes of homopolar bonds concentration hν

S-S

As-As + S-S → 2 As-S In general: aqueous base solvents - positive etching

M. Vlček.,S. Schroeter.,J. Čech, T. Wagner, T. Glaser J. of Non-Cryst. Solids 326&327 (2003) 515 – 518

38 non-aqueous solvents – negative etching

As2 S3

0,24

Mechanism of selective POSITIVE etching in aqueous solvents

AsS3

As40S60

0,20 0,18

I (arb. un.)

Dissolution of As2S3 and As4S4 crystals:

0,22

0,16 0,14

As-As

↔ As-As

Bulk

0,12

Annealed

0,10 0,08

Exposed

0,06

As2S3 + 6 OH- = AsO33- + AsS33- + 3 H2O well soluble

0,04

Virgin

0,02 0,00 100

200

300

400

500

S-S 600

-1

ν (cm )

3 As4S4 + 24 OH- = 4 AsO33- + 4 AsS33- + 4 As + 12 H2O low dissolution rate due to protective As film; insoluble in solutions with low concentration of OHGlassy samples: As4S4, As4S3 fragments present together with Sn fragments in the structure of virgin samples Exposure or annealing – chemical homogenisation, etching rate 39 increases due to decrease of activation energy of dissolution

Activation energy of dissolution in aqueous K2CO3 solution 1,1´ - As28S72 2,2´ - As40S60 3,3´ - As42S58 4,4´ - As45S55 X – virgin X´- exposed by halogen lamp, 14 mW.cm-2

M. Vlček, M. Frumar, M. Kubový, V. Nevšímalová J. Non-Cryst. Solids, 137-138 (1991) 1035

AsxS100-x films with x ≥ 40: virgin ∆E ≈ 90 kJ/mol exposed ∆E ≈ 40-50 kJ/mol with x < 40: virgin and exposed ∆E ≈ 45 kJ/mol

aqueous solvents - positive etching of As rich films

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Negative selective etching in non-aqueous base broad area continuous light

pulsed (16 ns) and continuous laser irradiation

below Bg

above Bg

As2S3, triethylamine, halogen lamp

As50Se50, ethanolamine, HeNe laser 10 mW, ArF laser (193 nm) 0,5-0,45 mJ single pulses, pulse width 16 ns, V. Lyubin et al.: J. Vac. Sci. Technol. B 15 (4) (1997) 823 41

Mechanism of NEGATIVE selective etching in non - aqueous amine based solvents Kinetically controlled process - the ultimate composition of the products is a function of the rate of elementary stages of a process Amines can promote the cleavage of sulfur rings (or chains) R3N + S8 = R3N+S8Exposed parts – ammonolysis of heteropolar bonds (slow process) As2S3 + 6 (C2H5)2NH = [(C2H5)2NH2]3AsS3 + As[(C2H5)2N]3 Unexposed part – breaking of polymeric network through homopolar bonds (faster process) (C2H5)2NH + Sn = (C2H5)2NH+Sn(C2H5)2NH+Sn- + As2S4/2 = (C2H5)2NH2+S-AsS2/2 + (C2H5)2NAsS2/2 42 cage type S.A. Zenkin, S.B. Mamedov, M.D. Mikailov, E. Yu. Turkina, I.Yu. Yusupov: Fizika i Khimiya Stekla 23 (5) (1997) 393

Raman spectra of As35S65 thin film Rea lga r Orpiment

Realgar

0,4

0,4

Rea lga r

virgin

O rpime nt Orpiment

0,2

Orpiment

S8

0,1

0,0

exposed 3 min

0,3

I (arb.un.)

I (arb.un.)

0,3

0,2

0,1

Sn

0,0

300

350

400

450

500

-1

ν (cm )

As2S3 - orpiment

550

300

400

500 -1

ν (cm )

As4S4 cages - realgar

As-As bonds containing species present even in the structure of S rich As-S films due to nanoscale phase separation of cages 43

Understanding the selective etching mechanism first step to achieve extremally high selectivity

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Etching bath

Aqueous base Positive etching

Organic amine base Negative etching !!!LOW SELECTIVITY!!! 45

How to achieve high selectivity of etching? Proper glass composition, proper conditions of deposition, proper exposure ………….. Modification of composition of etching bath - addition of redox agent into etching bath - addition of surface active substance (SAS) into etching bath

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Selectivity improvement - addition of reducing agent 1,0

2, 3, 4

virgin in bath w metol exposed (2’,3’,4’)

0,8

d/d 0

0,6

0,4

1´ 0,2

0,0

0

20

in bath w/o metol 2´ exposed virgin

40

60

80

1

3´

100

4´

120

140

time (s)

As2S3 film, etched in Na2CO3/Na3PO4+ metol, pH = 12. Concentration of metol (g/l): 1,1´- 0; 2,2´ - 0,1; 3,3´ – 0,2; 4,4´ - 0,3; 1´- 4´ exposure with mercury lamp I = 14 mW/cm-2 M. Vlček, M. Frumar, M. Kubový, V. Nevšímalová J. Non-Cryst. Solids, 137-138 (1991) 1035-1036

As2S3 + 6 OH- = AsO33- + AsS33- + 3 H2O 3 As4S4 + 24 OH- = 4 AsO33- + 4 AsS33- + 4 As + 12 H2O

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Selectivity improvement - addition of

surface active substancies (SAS) Anion-active SAS – sodium p-dodecylbenzenesulphite disodium bis-2-ethylhexylsuccinic disulphite Non-ionic SAS -

oxyethyl derivates of monoethanolaminesters

Cation-active SAS - cetyltrimethylammonium bromide benzenedodecyldimethylammonium bromide carboxypentadecyl-trimethylamonium chloride

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Addition of anion-active and/or non-ionic SAS

no selectivity of etching improvement – only slower rate for both 49

Addition of cation-active SAS

stopped fully!

cetyltrimethylammonium bromide M. Vlček, P. J. S. Ewen, T. Wagner J. of Non-Cryst. Solids 227-230 (1998) 743-747

It works!!! But how???

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How it works? What is function of cation-active SAS ? Structure of SAS: quaternary ammonium salts with long hydrophobic chain Preferably sorbed at the surface of unexposed samples, hydrophobic chain repulse OH- ions, etching rate decreases significantly OHOH OHOH0,24 0,22

As40S60

0,20

I (arb. un.)

0,18 0,16 0,14

Bulk

0,12

Annealed

0,10 0,08

SAS

Exposed

0,06

exposed

0,04

Virgin

0,02 0,00 100

200

300

400 -1

ν (cm )

500

600

virgin

As-As S-S 51

Conclusion - positive wet lithography exploit photostructural change in ChG and application of SAS produce extremally high positive selective etching in aqueous alkaline solvents

deposition of ChG

exposure

etching by aqueous alkaline solution

substrate (Cr, SiO2, Si3N4…) etching ChG layer removal

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Selectivity improvement – proper composition of CHG and proper exposure source As33S67 do = 3.7 μm UV lamp Exposure in air (sec) hν 1–0 2 – 30 3 – 60 4 – 90 5 – 120 TEA based solvent postponing in etching proportional to exposure dose even shaped structures can be etched 53

M. Vlček, P. J. S. Ewen, T. Wagner J. of Non-Cryst. Solids 227-230 (1998) 743-747

Micro-lens Array made by exposure with Halogen Lamp through Grey Mask

12 μm

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Conclusion - negative wet lithography exploit photostructural change in ChG extremally high negative selective etching in non-aqueous alkaline solvents can be achieved

deposition of ChG

Microlithography with gray scale mask

exposure

etching by amine based alkaline solution

substrate (Cr, SiO2, Si3N4…) etching

ChG layer removal

microlens arrays (12 μm diameter) in a thin As35S65 film, fabricated using a gray Cr mask. The focusing action of light by the 55 lenses is clearly seen.

Wet microlithography example – direct laser writing

S. Schröter, M. Vlcek, R. Pöhlmann, T. Glaser and H. Bartelt: Proceedings of MOC´04, Jena, Germany, September 2004

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Electron beam wet nanolithography

~ 100 nm

SEM pictures of pillar arrays in quadratic arrangement etched into As35S65. (a): diameter 122 nm, depth 410 nm, and period 400 nm (b): diameter 100 nm, depth 410 nm, and period 300 nm (c,d): diameter less than 100 nm, depth 300 nm, and period 350 nm, displayed at different magnifications 57

S. Schröter, M. Vlcek, R. Pöhlmann, T. Glaser and H. Bartelt: Proceedings of MOC´04, Jena, Germany, September 2004

!!!Wet macrolithography!!! Green tower, Pardubice, Czech Republic

↔ 100 km

in real

in chromium

58 http://www.pardubice.cz/

What is the resolution limit of CHG etching?

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Resolution capability

AFM Data Linear Fit

Wheel Height (nm)

240 200 160 120 80 40 0

2

4

6

8

10

Electron Dose (a.u.) M. Vlcek, H.Jain J. of Optoelectronics and Advanced Materials 8 (6) (2006) 2108 - 2111

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Resolution limit – 7 nm???

a

or less???? b

JAMIE!!!

SEM picture of a nanograting fabricated in As-S film by electron beam exposure followed by development in amine based solvent. Stage tilt of 45o at 15 kV. Grooves width 14 nm. M. Vlcek, H.Jain J. of Optoelectronics and Advanced Materials 8 (6) (2006) 2108 – 2111

Figure 2(a) shows various vertical lines that are 27 nm wide and have gap separations of only 7 nm. In Figure 2(b) a tilted SEM image shows the topography of the grating structure. Heights of the individual lines ~80-90 nm tall J.R. Neilson, A. Kovalskiy, M. Vlček, H. Jain, F. Miller J. of Non-Cryst. Solids 353 (13-15) (2007) 1427-1430

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Some examples of micro and nanostructuring of CHG and/or their exploitation to transfer patterns into other materials

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Direct laser writing at 442 nm, wet etching

D i r e c

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Holographic exposure

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A.V. Stronski, M. Vlcek, A. Sklenar, P.E. Shepeljavi, S.A. Kostyukevich, T. Wagner J. of Non-Cryst. Solids 266-269 (2000) 973-978

DLW of 3D photonic crystal structures

66 S. Wong at al. Adv. Matter. 18 (2006) 265 - 269

Transparent and semitransparent holograms

M. Vlček, A. Sklenář: Transparent and Semitransparent Diffractive Elements, Particularly Holograms and Their Making Process, US patent 6,452,698 B1, 17. 9. 2002. Canada (CA 2,323,474), Japan (JP 2002 507770 T), EU (EP1062547o), former USSR states (EA2393), Slovakia (SK 13552000) 67

Direct microstructuring (no etching best etching)

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Photoinduced local oxidation

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Photoinduced local corrugation by high energy high intensity beam

Corrugation Depth

Local heating close to T g

Corrugated result

Surface corrugation power treshold

Optical Power 70

Laser writer DWL 66-UV, 244 nm – doubled Ar laser

exposed

Grating in As35S65 layer with period of 1.28 μm, and grooves of 160 nm bottom width and 640 nm depth, written with beam power of 400 mW at a scanning speed of 30 mm/s

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T. Glaser, S. Schroter, S. Fehling, R. Pohlmann and M. Vlcek ELECTRONICS LETTERS 40 (3) (2004) 176 - 177

Laser writer DWL 66-UV, 244 nm – doubled Ar laser

SEM pictures of 2D gratings fabricated by direct DUV laser writing technique and consisting of a trigonal air hole pattern written with a period of 2.2 μm designed to exhibit hexagonal holes of 1.6 μm width across flats in a 700 nm thick layer of As35S65 written at 0.4 mW (up), 0.5 mW (left) and 0.8 mW (right) imaged at 75°. For 0.5 mW the exposed power intensity and dose are 0.7 MW/cm2 and 2.6 J/cm2. 72 S. Schroeter, M. Vlcek, R. Poehlmann, A. Fiserova Journal of Physics and Chemistry of Solids 68 ( 5-6) (2007) 916-919

Laser writer DWL 66-UV, 244 nm – doubled Ar laser

S. Schroeter, M. Vlcek, R. Poehlmann, A. Fiserova Journal of Physics and Chemistry of Solids 68 ( 5-6) (2007) 916-919

73

Summary Glasses, mainly some chalcogenide glasses, can be applied as highly sensitive resists with extraordinary resolution going down to nanometers size both, positive and negative resists can be achieved Easy to prepare large array films with controlable thickness, good adhesion to Si, SiO2 , Si3N4 …, and strong resistance to HF, H2SO4 , H3PO4 , HCl…and or gasses as CF4 direct structuring using high energy high intensity beam 3 D nanostructures can be fabricated in CHG using UVDLW and/or electron beam lithography down to 100 nm and 10 nm, respectively 74

Do you know now the answers? • What is lithography? What is glass? • Can glass be photosensitive? • Can glass be selectively etched/featured? If yes, how and what is the resolution limit? • Can a glass be applied in lithographic process and vice versa can lithography be applied to structure glasses?

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And still something pleasant before I say you GOODBYE

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Prof. Himanshu Jain – winner of Otto Schott Research Award – 2007 Director of IMI

- outstanding work towards advancing fundamental understanding of the movements of atoms inside glass - research into unique light-induced phenomena in glass - studies of the corrosion of glass in nuclear environments - studies in the field of sensors, infrared optics, waveguides, photolithography, 77 nanolithography and other photonic applications of glass

Thank you for your attention Your feedback highly appreciated at: [email protected] or [email protected]

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GOODBYE!!!

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